T-cells play a pivotal role in cellular and humoral immune response and can mediate the functions of other immune system cells (e.g., B-cells, leukocytes, or macrophages). Type I and type II helper T-cells are regulated by autocrine and paracrine factors such as cytokines, a class of secreted immunomodulatory proteins expressed primarily in T-cells.
Cytokines are implicated in immune responses, including proliferation, activation, and differentiation of T-cells. For example, interferon γ (IFN γ) stimulates inflammation, antitumoral response, antiviral response, and T-cell differentiation. Interleukin 2 (IL-2), secreted by activated T-lymphocytes, is essential for T-cell function. Thus, cytokines are powerful immunostimulants, and can be administered exogenously to stimulate an immune response in a patient. However, administering an exogenous cytokine presents a number of difficulties. First, the production of large quantities of high purity cytokines is technically demanding and very expensive. Second, due to their lability, cytokines must be prevented from degrading or inactivating before use. Finally, an exogenous cytokine may trigger an allergic reaction.
Thus, there is a need for inexpensive and stable compositions for increasing endogenous cytokine levels, as well as methods for identifying and using such compositions.